1. Field of the Invention
The present invention relates to a small printer which uses a character member, such as a character ring or a character belt. The character member comprises linked dot character bodies that each have a dot character on the top face thereof. The present invention prints characters on a print paper by striking the character bodies with a hammer. More particularly, the invention relates to the arrangement of the dot characters on the character member and a print mechanism that uses the dot character arrangements.
2. Discussion of the Related Art
Several small printers that use a character rings or character belts which comprise a number of linked characters are known. Published Unexamined Japanese Patent Application No. Sho. 62-119054 discloses a small printer which utilizes a character drum that is elongated in the horizontal direction. A character sheet having a plurality of dot characters are wound around the drum.
Published Unexamined Japanese Patent Application No. Sho. 57-128567 also discloses a small printer that comprises a character drum which is elongated in the horizontal position. Character rings that each have a plurality of dot characters are wound around the drum, and the number of the character rings is equal to the number of character positions of one line of text to be printed.
In addition, Published Unexamined Japanese Patent Application No. Sho. 56-38275 discloses a small printer which is similar to the printer disclosed in Published Unexamined Japanese Patent Application No. Sho. 57-128567.
The conventional small printers which use conventional character drums, character sheets, or character rings have several problems. For instance, the size of the conventional character ring cannot be reduced. Accordingly, there is a limit in further reducing the size of the printer and further reducing the cost of manufacturing the printer. In addition, the conventional small printers do not have the ability to print graphics.
In the printer of Published Unexamined Japanese Patent Application No. Sho. 62-119054, a protrusion on the character sheet which forms one dot is located at a character position. A standard text character is 5 dots (or 5 character positions) wide and 7 dots (or 7 character positions) tall. Therefore, a standard text character may be represented by a matrix of 7 dots.times.5 dots (i.e., a matrix consisting of 7 dots in the vertical or column direction and 5 dots in the horizontal or row direction). Consequently, in the printer disclosed in the publication, a total of 35 (7.times.5) character positions must be used. Thus, the size of the character sheet limits the ability to reduce the size of the printer.
In addition, the print operation is repeated a plurality of times at the same horizontal location of the line of text. Therefore, when a printer is used as a character-type serial printer, a print/character advance operation must be repeated each time the character sheet is horizontally advanced. Consequently, serial printers using the printing technique disclosed in the publication are expensive.
Also, when using the above printing technique, the printing hammer, which creates a printed dot on the paper by striking a character position on the character sheet, strikes the character sheet at a point which is significantly displaced from the dot-like protrusion. Consequently, the printed characters become chipped and are smudged due to the hammer inadvertently striking a portion of an adjacent character position. Additionally, it is impossible to print characters of different sizes and fonts since only one type of dot is used.
Furthermore, in the conventional printers, the character member takes the form of a long drum with a large diameter. Thus, the size of the drum limits the ability to reduce the size of the printer.
In addition, the printers disclosed in Published Unexamined Japanese Patent Application Nos. Sho. 57-128567 and 56-38275 require a character member for each character to be printed in a line of text. This requirement increases the number of required parts, limits the ability to reduce the size of the printers, and increases the cost of the printers. Also, since there are many character rings, it is impossible to provide adequate spacing between the adjacent character rings. Therefore, an area located outside the vicinity of the character rings is required in which to connect the hammer lever to the hammer drive solenoid. In addition, in order to prevent the printed characters from becoming smudged, a fixed space is required to prevent the adjacent character rings from interfering with one another. Finally, the printers disclosed in the publications are not suitable for printing graphics, patterns, and characters of desired sizes and fonts. This problem becomes even more serious when the dot pitches are reduced to improve the resolution of the printed characters.
An object of the present invention is to provide a printer with a character member containing dot characters, which is inexpensive and is capable of printing graphics.
Another object of the present invention is to provide a small printer, which includes a character member that does not print chipped or smudged characters, includes a drive mechanism for driving the character member, and is capable of printing high quality characters at a high resolution.
Yet another object of the present invention is to provide a small printer with a character member which enables the printer to print characters of different sizes and fonts.
Still another object of the present invention is to provide a small dot matrix printer which prints one line at equal pitches with a single character belt.